The invention pertains to a rotatable cutting tool that is useful for the impingement of earth strata such as, for example, asphaltic roadway material, coal deposits, mineral formations and the like. More specifically, the present invention pertains to a rotatable cutting tool that is useful for the impingement of earth strata wherein the cutting tool body possesses improved design so as to provide for improved performance characteristics for the rotatable cutting tool.
Rotatable cutting tools have been used to impinge earth strata such as, for example, asphaltic roadway material or ore bearing or coal bearing earth formations or the like. Generally speaking, these kinds of rotatable cutting tools have an elongate cutting tool body (typically made from steel) and a hard tip (or insert) affixed to the cutting tool body at the axial forward end thereof. The hard tip is typically made from a hard material such as, for example, cemented (cobalt) tungsten carbide. The rotatable cutting tool is rotatably retained or held in the bore of a tool holder or, in the alternative, in the bore of a sleeve that is in turn held in the bore of a holder.
The holder is affixed to a driven member such as, for example, a driven drum of a road planing machine. In some designs, the driven member (e.g., drum) carries hundreds of holders wherein each holder carries a rotatable cutting tool. Hence, the driven member may carry hundreds of rotatable cutting tools. The driven member is driven (e.g., rotated) such that the hard tip of each one of the rotatable cutting tools impinges or impacts the earth strata (e.g., asphaltic roadway material) thereby fracturing and breaking up the material into debris.
As can be appreciated, during operation the entire rotatable cutting tool is typically subjected to a variety of extreme cutting forces and stresses in an abrasive and erosive environment. Rotatable cutting tools having a cutting tool body with various shapes and designs have been provided to most efficiently and effectively operate in these extreme cutting environments. However, it would be undesirable for the cutting tool body to prematurely wear or fail (whether it be through catastrophic fracture or the like or through abrasive or erosive wear) prior to the hard cutting tip wearing to the point of its useful life. In such a circumstance, the rotatable cutting tool would have to be replaced prior to the normally scheduled time for replacement. Further, the premature failure of the rotatable cutting tool would negatively impact the cutting or milling efficiency of the overall earthworking apparatus. It thus becomes apparent that it is important and desirable that the cutting tool body possess the requisite design and strength to maintain its integrity during the intended useful life of the rotatable cutting tool while still providing an efficient and effective rotatable cutting tool.